class Solution {
public:
    int wiggleMaxLength(vector<int>& nums) {
        int n=nums.size();
        if(n<2)return n;
        int ret=0,left=0;
        for(int i=0;i<n-1;i++)
        {
            int right=nums[i+1]-nums[i];
            if(right==0)continue;
            if(right*left<=0)ret++;
            left=right;
        }
        return ret+1;
    }
};
